Biomechanical models predicting plaque rupture and device-tissue interactions rely on accurate material properties to produce reliable simulation results. However, there is a wide variation in the reported stiffness properties for advanced atherosclerotic lesions. The purpose of this study was to characterise isolated calcified and non-calcified portions of ex vivo carotid atherosclerotic tissues using nanomechanical techniques and compare the results against those from previous studies. Eleven carotid plaque samples were acquired from patients undergoing endarterectomy. Calcification was characterised using traditional instrumented indentation (TII) (n = 06). Micro-Computed Tomography was used to identify areas of calcification. Ferrule-top cantilever nanoindentation (FTC) was conducted on non-calcified tissue regions (n = 05). Adjacent tissue slices were stained with Alizarin Red to select regions of non-calcified tissue for testing. Scanning electron microscopy was employed to qualitatively assess the calcified and non-calcified samples’ surface roughness. The results from this study demonstrate over 6 orders of magnitude difference in stiffness between the elastic moduli of calcified (22.40 [17.70–27.55] GPa) and non-calcified (8.16 [3.85–14.78] kPa) carotid atherosclerotic tissues. Microscopy analysis indicates a larger variation in surface roughness produced with non-calcified tissue cryosectioning than with calcified tissue metallographic preparation, which may account for the increased amount of indent failures with FTC (32%) than with TII (11%). Performing high-resolution imaging and nanomechanical approaches in parallel produce results that clarify the wide range in reported properties for advanced atherosclerotic lesions. Future studies should examine the viscoelastic nature of diseased human arterial tissues.

中文翻译：

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动脉粥样硬化组织钙化和非钙化成分的纳米压痕

预测斑块破裂和设备-组织相互作用的生物力学模型依赖于准确的材料特性来产生可靠的模拟结果。然而，所报告的晚期动脉粥样硬化病变的刚度特性存在很大差异。本研究的目的是使用纳米力学技术表征离体颈动脉粥样硬化组织的孤立钙化和非钙化部分，并将结果与​​先前研究的结果进行比较。从接受动脉内膜切除术的患者中获得了 11 个颈动脉斑块样本。使用传统仪器压痕 (TII) (n = 06) 表征钙化。微计算机断层扫描用于识别钙化区域。在非钙化组织区域 (n = 05) 上进行了套圈顶部悬臂纳米压痕 (FTC)。相邻的组织切片用茜素红染色，以选择非钙化组织的区域进行测试。采用扫描电子显微镜对钙化和非钙化样品的表面粗糙度进行定性评估。这项研究的结果表明，钙化 (22.40 [17.70–27.55] GPa) 和非钙化 (8.16 [3.85–14.78] kPa) 颈动脉粥样硬化组织的弹性模量之间存在超过 6 个数量级的刚度差异。显微镜分析表明，与钙化组织金相制备相比，非钙化组织冷冻切片产生的表面粗糙度变化更大，这可能是 FTC (32%) 比 TII (11%) 压痕失败量增加的原因。并行执行高分辨率成像和纳米机械方法产生的结果阐明了晚期动脉粥样硬化病变报告特性的广泛范围。未来的研究应该检查患病的人类动脉组织的粘弹性。